From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F2BE31547E0; Mon, 5 Aug 2024 11:44:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722858286; cv=none; b=UR1t8rluGwRvFKUwlNUXZ2o4Ar+Kiwq0kXKhe5c8ZetDv9mzeZGmFDOyNZuBxn+bca4ZG/kpV9e/3O6A7E+Ozhffow55AS7BHFea5iB8lMUPSLrZIJLSmRBfg2HDeoH7+rJ57Ut1aMs8cjC1yXrShZTTxrwwkDqXEnWvLeHV/aA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722858286; c=relaxed/simple; bh=psjqkvSz6om6QMnXQwEc9G30bmFNifSE/T8EH9Ag1xM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=E065YY16oFkoJCkH27QVWCi8ABBXWOEFVq6OmbhrS2/2+cxvGcmPPflTvudEnqFvy8NzVxIBt8pf1YBEhYgDkXfuhk7nIRoklu68+eraJ/miLzyH130+CuQDRSzowJZKVktBMIEHYFaFuLTFFDzNrrdlKlvfSI+q2RAzVd7bHhE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=rdY54jwi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="rdY54jwi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 64F45C32782; Mon, 5 Aug 2024 11:44:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1722858285; bh=psjqkvSz6om6QMnXQwEc9G30bmFNifSE/T8EH9Ag1xM=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rdY54jwiesJ8buhej7fdZ6PHEznwgxSSQ9wTdYn9AxsFZAU1kyFnHxR9OiUodo+iO Fisc9Ies/PCFTFMHV/93WUBdiP02DXmZyI6OuwkAQxHiVQiSc/zhduwJrCbGo/MOaN 9/F07jIPxEEnPNHd+97SjCxQUcqbBydwq7k3B7X8XC0bKbhqK7E9AxOHyXD4NQZ45Z E+/7YzQBIcQ7waV9VgDLCJfN27gupKHJKzvP3OTy8f2zN45biSmyZMKv0kMRf8i6ru 43rEAWKJC7kbkmAnb8R9gVPNi1vy21+q3dWvSG3Bj7sOa4V9x6wJkKfmdegkvFa4XI XNzNVb16V8Qlg== Date: Mon, 5 Aug 2024 13:44:40 +0200 From: Christian Brauner To: Jeff Layton Cc: Mateusz Guzik , Alexander Viro , Jan Kara , Andrew Morton , Josef Bacik , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC 3/4] lockref: rework CMPXCHG_LOOP to handle contention better Message-ID: <20240805-unser-viren-4f1860143b6e@brauner> References: <20240802-openfast-v1-0-a1cff2a33063@kernel.org> <20240802-openfast-v1-3-a1cff2a33063@kernel.org> <7ff040d4a0fb1634d3dc9282da014165a347dbb2.camel@kernel.org> <808181ffe87d83f8cb36ebb4afbf6cd90778c763.camel@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <808181ffe87d83f8cb36ebb4afbf6cd90778c763.camel@kernel.org> > Audit not my favorite area of the kernel to work in either. I don't see > a good way to make it rcu-friendly, but I haven't looked too hard yet > either. It would be nice to be able to do some of the auditing under > rcu or spinlock. For audit your main option is to dodge the problem and check whether audit is active and only drop out of rcu if it is. That sidesteps the problem. I'm somewhat certain that a lot of systems don't really have audit active. >From a brief look at audit it would be quite involved to make it work just under rcu. Not just because it does various allocation but it also reads fscaps from disk and so on. That's not going to work unless we add a vfs based fscaps cache similar to what we do for acls. I find that very unlikely.